Year	Percent change (Units)
1987	0.541
1988	11.462
1989	7.643
1990	2.911
1991	6.909
1992	0.253
1993	-2.052
1994	6.897
1995	8.401
1996	-1.190
1997	12.970
1998	9.633
1999	5.709
2000	16.211
2001	8.961
2002	-2.296
2003	-0.175
2004	6.501
2005	-2.711
2006	13.401
2007	2.059
2008	9.135
2009	-19.531
2010	27.048
2011	13.779
2012	-1.982
2013	3.446
2014	1.292
2015	-4.203
2016	0.493
2017	5.728
2018	0.540
2019	1.428
2020	-10.324
2021	3.777
2022	-3.961
2023	-0.477
2024	0.271
2025	2.500
2026	2.450
2027	2.400
2028	2.400
2029	2.400